=begin rdoc
RRDtool is the Open Source industry standard, high performance data logging and graphing system for time series data.
RRD stands for "Round Robin Database". It stores data in a very compact way that will not expand over time.

RRDTool is a really good back-end for storing time-series data. If you are developing tools that need a data repository 
and graphing capabilities, this provides you both. You create an RRD and then you begin inserting data values at regular 
intervals. You then call the graphing API to have a graph displayed. The neat thing about this data storage is its 
"round robin" nature. You define various time spans, and the granularity at which you want them stored. A fixed binary 
file is created, which never grows in size over time. As you insert more data, it is inserted into each span. 
As results are collected, they are averaged and rolled into successive time spans. It makes a much more efficient system 
than using your own complex data structures, relational database, or file system storage. 
=end
